shapes of complex ions

• ligand

  molecule that forms a coordinate bond with a transition metal by donating a pair of electrons
• coordination number

  number of coordinate bonds to the molecule
• lewis base:

  lone pair donor
• lewis acid

  lone pair acceptor
• linear shape - complex ion

  2 coordination number

  linear shape (180)
• square planar shape - complex ion

  4 coordination number

  right angles (90)

  occurs in Pt and Ni
• tetrahedral shape - complex ion

  • 4 coordination number
  • occurs with larger ligands (Cl-)
• octahedral shape - complex ion

  • 6 coordination number
  • occurs with eg: NH3, H2O
• unidentate ligand

  forms 1 co-ordinate bond (has only 1 lone pair) to an ion

  eg: H2O, Cl, NH3
• multidentate ligand

  forms more than 1 co-ordinate bond (has more than 1 lone pair) to an ion

  eg: EDTA
• where does cis-trans isomerism occur

  octahedral

  square planar
• structure of cisplatin:

  
• where does optical isomerism occur

  bidentate ligands - octahedral
• chelate effect:

  • entropy value is always positive - increase in number of particles
  • enthalpy change is negligible - very small
  • gibbs free energy will always be negative